The present invention relates generally to fuel cells and, more particularly, to fuel cells used to supplement power sources for aircraft equipment.
Modern aircraft include a variety of electrical devices. One airplane may include navigational equipment, communications equipment such as a radio, and emergency equipment such as an emergency locator transmitter. These devices may be embodied in individual cases or boxes known as line-replaceable units (LRUs).
Typically, power may be provided to an LRU from a power system powered primarily by one or more generators, each of which may be coupled to an aircraft engine. Additionally, a power system may receive power from an auxiliary power unit, such as a gas turbine.
Battery power may be used as a backup power supply for an LRU in the event of a power system failure due to, for example, loss of engine power. Similarly, capacitors may also be used to supply backup power to an LRU. Battery and capacitor backups (both of which may be referred to as “battery”, “battery backup”, or “battery power” herein) may enable an LRU to continue to operate even though no power is being received from the power system. Battery power may provide backup power supply for a limited time. Increasing the number of batteries may increase the amount of time that backup power is available. However, an increased number of batteries means an increased amount of weight.
In the event of a partial or complete power system failure, an aircraft crew may begin shutting down non-essential electrical systems in order to prolong backup power. The order in which non-essential electrical systems are shut down may be suggested by, for example, guideline, regulation, or accepted practice. There may, however, be certain essential items that the crew may want to avoid shutting down. For example, due to the specifics of the particular situation, the crew may want to keep a radio operational for as long as possible so as to request emergency assistance. If the crew keeps the radio on, the battery backup may eventually run out of energy and the radio will no longer function.
As can be seen, there is a need for a way to provide or supplement the supply of power to an LRU when power is otherwise unavailable from a normal power system. There is a need for a way to provide or supplement the supply of power that weighs less than conventional batteries. There is a need for a way to efficiently and practically provide or supplement the supply of power.